Machine gun



/7 Inventur- Jahn L Lnchhead 12V MMfff/M Attorney Patented June 25, i940 UNITED STATES ortica 4 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Goverment for governmental purposes, without the payment to me of any royalty thereon.

'Ihis invention relates to a machine gun and more particularly it has reference to means for cooling the barrel of the gun.

In machine guns of the water-cooled type a portion of the barrel is surrounded by a jacket which contains a cooling medium such as water. During continuous firing of the gun the water is heated and the steam that is generated is conducted to a Water box where it is condensed. The water supply in the jacket requires frequent renewal and under the present system of operation this necessitates an interruption in firing, disarranges the setting of the gun, oods the operative elements adjacent the feed mechanism, requires exposure of the operator who performs the task, and frequently by reason of the restricted clearance imposed by the nature of the gun emplacement demands lowering of the gun mount.

With a view to overcoming the objections outlined above the present invention contemplates the provision of a pumping apparatus which is operated by a, portion of the gases of the propellent charge and which circulates the cooling fluid. The installation is especially arranged to conduct the cooling fluid to the breech of the gun barrel.

To these and other ends, the invention consistsin the construction, arrangement and combination of elements described hereinafter and pointed out in the claims forming a part of this specification.

A practical embodiment of the invention is illustrated in the accompanying drawing, wherein:

Fig. 1 is a view in side elevation of a machine gun equipped with the improved pump unit;

Fig. 2 is an enlarged longitudinal sectional view of the front part of the unit;

Fig. 3 is a similar view of the rear part of the unit;

Fig. 4 is a View in front elevation of the gun;

Fig. 5 is a view in side elevation of the blade propeller;

Fig. 6 is a view in front elevation of the blade propeller.

Referring to the drawing by characters of reference there is shown a support 5 which is a part of the receiver of `a machine gun of the Browning type and carries a jacket 5 for a cooling fluid. The front plate 1 of the jacket is formed with a bearing 8 for slidably mounting a sleeve 8 on the muzzle of a barrel I0. Packing II between the sleeve and bearing is retained by a gland I2. The breech end of the barrel extends through the support 5, and its rear portion being slidably supported therein while its front portion is spaced from the support to be surrounded` by the cooling uid which passes through an opening I3 between the support 5 and the jacket 6. A more or less conventional muzzle brake and recoil check is mounted by the front plate 1 of the jacket and comprises a casing I5 which carries a baille I6 through which the bullet passes.

A uid line or tube I1 extending along the under side of the jacket 6 has its rear end connected to a fluid container I8 which is carried by the support 5 while its front end is mounted in a casing I9 which is attached to the jacket. A ud passage 28 is provided to establish communication between the container I8 and the support 5 and a passage 2| is provided to establish communication between the tube and the jacket.

A pump for circulating the cooling uid through the system comprises a screw propeller 22 which is located in the tube I1 in rear of the passage 2|. The screw propeller is provided on the rear end of ashaft 23 which has a journal 24 mounted in a bearing 25 that is threaded in the casing and serves as a gland to retain a packing 26 against the front end of the tube.

The front end of the shaft carries a blade propeller 21 whose hub 28 is mounted in the bearing 29 of a bracket 38 attached to the casing I5 and whose blades are disposed in a recess 3| of the bracket and confined therein by a retaining member 32 threaded to the bracket. The blades of the blade propeller 21 are each formed with an inclined surface 33 which deflects gases through vents 34 in the retaining member 32. The gases which supply the force for rotating the shaft 23 are received from the muzzle attachment during ring of the gun and are directed onto the blades after passing through aligned ports 35'and 36 respectively in the casing I5 and bracket 38. Alignment of the ports is assured by means of interfltting parts consisting of a pin 31 on the casing and a recess 38 in the rear face of the bracket.

The bracket 30 is secured in place by means of a clamp 39 embracing the casing I5 and also by means of a screw 40 passing through the bracket and entering the front plate 1. The bracket also receives a locating pin 4I which engages the front plate and assures vertical alignment.

When the gun is being red the gases from the propelling charge expand in the casing I5 and act on the baille i6. A portion of the gases flow through the ports 35 and 36 and are directed onto the blade propeller 21 which is caused to rotate and drive the shaft 23, carrying the screw propeller 22 in the tube I1. The screw propeller forces the cooling medium rearwardly through the tube and maintains its circulation through the system. Since the gun is normally in elevated position when firing, the cooling medium, as it becomes heated, rises to the front end of the jacket. The gas-driven pump in circulating the fluid provides for more effective cooling of the barrel. The uid in passing through the tube l1 is cooled and it is to be understood that the tube l1 comprises or forms part of a cooling system and that its extent, capacity and arrangement are not limited by the particular illustration of the drawing. The provision of the fluid container Vi8 on the support 5 enables the breech of the barrel to be effectively cooled.

I claim:

1. In a machine gun, a support, a jacket carried by the support and having iiuld communication with the support, a gun barrel passing throughthe jacket and slidably mounted in the front of the jacket and in the support, a recoil check on the front of the jacket and having a gas port, a containe'r carried by the support and having fluid communication therewith, a casing on the jacket, a tube between the container and casing, a fluid passage in the tube, casing and jacket, a bracket on the recoil check and having a gas port aligned with the gas port of the recoil check, a shaft mounted in the bracket and in the casing, a screw propeller on theshaft and disposed in the tube, and a blade propeller on the shaft disposed in the bracket and adapted to be driven by gases passing through the gas ports.

2. In a machine gun, a support, a jacket carried by the support and having iiuid communication with the support, a gun barrel passing through the jacket and slidably mounted in the front of the jacket and in the support, a recoil check on the front of the jacket and having a gas port, a container carried by the support and having fluid communication therewith, a fluid line between the container and the front part of the jacket, a bracket on the recoil check and having a gas port aligned with the gas port of the recoil check, a shaft having a screw propeller in the uid lineand a blade propeller in the bracket adapted to be driven by gases passing through the gas ports.

3. In a machine gun, a support, a jacket carried by the support and having fluid communication with the support, a gun barrel passing through the jacket and slidably mounted in the front of the jacket and in the support, a container carried by the support and having fluid communication therewith, a fluid line between the container and the front part of the jacket, a shaft having a vscrew propeller in the fluid line, a blade propeller on said shaft, and means for directing gases from the gun barrel onto the blade propeller.

4. In a gun, a barrel, a jacket including a circulatory system surrounding the barrel and adapted to contain a cooling fluid, a shaft having a screw propeller in the circulatory system, a blade propeller on said shaft, and means for directing gases from the barrel onto the blade propeller.

. JOHN L. LOCHHEAD. 

